Madecassoside ameliorates lipopolysaccharide-induced neurotoxicity in rats by activating the Nrf2-HO-1 pathway

Neuroinflammation is a predisposing factor for several neurodegenerative diseases. The purpose of this study was to evaluate the protective effect of madecassoside (MA) in lipopolysaccharide (LPS)-induced cognitive impairment and neuroinflammation in rats. MA has many protective effects such as antioxidant and anti-inflammatory properties. We investigated whether MA could improve neurocognitive dysfunction caused by intracerebroventricular injection of LPS. We examined the effects and mechanisms of action of MA on LPS-induced neuroinflammation in the cortex and hippocampus. Our study revealed that MA (120 mg/kg, i.g) treatment for 14 days reduced LPS-induced neurotoxicity by reducing cognitive impairments and suppressing the production of inflammatory cytokines such as interleukin 1 beta (IL-1β), tumor necrosis factor alpha(TNF-α), and interleukin 6(IL-6) via activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Furthermore, MA treatment enhanced protein levels of heme oxygenase (HO)-1 by upregulating Nrf2 in LPS-stimulated neurotoxicity. Collectively, these results suggest that MA is effective in preventing neurodegenerative diseases by improving memory functions due to its anti-inflammatory activities and activation of Keap1-Nrf2/HO-1 signaling. As such, MA may be a potential therapy for addressing memory impairment caused by neuroinflammation.